I have had many great teachers throughout my education, and both Larry and Dave rank right up there, too. Both have decades of experience living and teaching in Japan, so they are filled to the brim with useful knowledge that useful not just for teaching in Japan, but also living there. To top it all off, they both happen to be really great, personable, and humorous guys.
I also want to give a word of warning; don't expect a walk in the park. Within these four weeks you will learn more about grammar than you ever knew existed and the workload, while not backbreaking, will definitely consume a fair amount of time.
What would you improve about this program?
My only real complaint is that the classroom can feel a little cramped.